206 THE OLFACTORY ORGAN, BY PROFESSOR BABUCHIN. 



appears that the epithelial portion of the olfactory organ is 

 constructed upon one and the same type in all Vertebrata, so that 

 the description of its structure in any one animal is applicable 

 to all. We shall therefore select an animal whose epithelial 

 cells are large and easily isolable, as the Proteus, in which the 

 histological elements attain an almost colossal size, and have 

 nevertheless been as yet but little examined. If now the 

 entire olfactory organ of a Proteus be macerated for a day in 

 Miiller's fluid, then be transferred for the same space of time to 

 distilled water, and finally a fragment be torn away from the 

 olfactory region, we shall see distinctly how the epithelial cells 

 split up into distinct cell groups (fig. 339). In these groups we 

 distinguish an external half, composed apparently of extremely 

 fine fibrils, which at their outer extremities terminate in long 

 fine cilia, and an internal half, composed of large closely com- 

 pressed nuclei, of which one is larger than the remainder, presents 

 an elongated oval form, and is for the most part situated ex- 

 ternally. Further manipulation with needles shows that each 

 of the above-described groups consists of two kinds of cells, 

 some few of which are large, whilst the greater number have 

 a large round nucleus and very long fine processes (fig. 340). 

 One of these processes, and indeed the thicker of the two, 

 runs outwards, the other is very fine, is directed inwards, and 

 can be followed to the margin of the subepithelial connective 

 tissue. These are the olfactory cells of Max Schultze which 

 conduct the impressions of smell. Their outer extremity 

 bears the above-named long and fine cilia,* and appears in pre- 

 parations which have been macerated in Miiller's fluid sinu- 

 ously curved, and as it were in zigzags. In specimens prepared 

 with chloride of gold, or in those which have been treated with 

 sulphuric acid, these processes present the appearance of very 

 fine and varicose fibres. By the use of high powers it may be 

 demonstrated that a continuous fine fibre runs through all the 



* The apparent difference of the above from Max Schultze's observa- 

 tions, according to whom the cilia are absent in the Proteus, and as in 

 branchiated animals, must necessarily be absent, can only arise from the 

 circumstance that this most careful inquirer had only animals at his com- 

 mand that had long been preserved in solution of chromic acid. 



